Carpal tunnel syndrome is a common problem that affects the hand and wrist. This condition, or syndrome, has become the focus of much attention in the last few years due to suggestions that it may be linked to certain occupations that require repetitive use of the hands, such as typing. While certain occupations may experience more problems with carpal tunnel syndrome, many people develop this condition regardless of their occupation.
Particularly, carpal tunnel syndrome (CTS) is a condition that results when the median nerve of the hand does not function properly. Usually, this occurs because there is too much pressure on the median nerve that extends into the wrist through an opening called the carpal tunnel. The median nerve extends into the hand to receive sensation from the thumb, index finger, long finger, and half of the ring finger. The median nerve also provides a branch to the muscles of the thumb (i.e. the thenar muscles).
The carpal tunnel is an opening into the hand that is made up of the bones of the wrist (i.e. the carpals) on the bottom and the transverse carpal ligament on the top. The median nerve and the flexor tendons extend through the carpal tunnel into the hand. The median nerve lies just under the transverse carpal ligament. A material called the tenosynovium covers the flexor tendons. The tenosynovium is slippery and thus allows the tendons to glide against each other as they move. Any condition that causes irritation or inflammation of the tendons can result in swelling and/or thickening of the tenosynovium. As the tenosynovium begins to swell and/or thicken, pressure begins to increase in the carpal tunnel. This is because the bones and ligaments that constitute the carpel tunnel are fixed in size and thus are not able to stretch in response to the swelling. Increased pressure in the carpel tunnel begins to squeeze the median nerve against the transverse carpal ligament, since the median nerve is the softest structure in the carpal tunnel. Eventually, the pressure reaches a point where the median nerve can no longer function normally. This manifests itself as pain and numbness in the hand.
There are many conditions that can result in irritation and inflammation of the tenosynovium, and eventually cause carpal tunnel syndrome. Different types of arthritis can cause inflammation of the tenosynovium directly. A fracture of the wrist bones may later cause carpal tunnel syndrome if the healed fragments result in abnormal irritation on the flexor tendons. Particularly, anything that causes abnormal pressure on the median nerve will result in the symptoms of carpal tunnel syndrome.
In the early stages of carpal tunnel syndrome, non-operative treatments are typically used. One such non-operative treatment is the use of a brace. The brace keeps the wrist in a neutral position. When the wrist is in a neutral position, the carpal tunnel is as large as it can be so the median nerve has as much room as possible.
Another non-operative treatment that tries to reduce the symptoms of carpal tunnel syndrome is the use of anti-inflammatory medications to help control swelling of the tenosynovium. Anti-inflammatory medications include over the counter medications such as ibuprofen and aspirin, as well as high doses of vitamin B-6. Injections of cortisone into the carpal tunnel may also be used in order to decrease swelling of the tenosynovium and thereby give temporary relief of symptoms.
If the non-operative treatments fail to control the symptoms of carpal tunnel syndrome, surgery may be required to reduce the pressure on the median nerve. There are essentially three surgical techniques designed to relieve pressure on the median nerve. The first and most common surgical procedure is the traditional open incision technique. A second surgical procedure is known as a mini-open. The third procedure is an endoscopic technique.
The traditional open incision technique requires a 2 to 2½ inch incision to be made in the palm of the hand. A structure called the palmer fascia is then incised in order to reach the transverse carpal ligament. The transverse carpal ligament is then cut while making sure that the median nerve is out of the way and protected. The cut or incision may e slight (small incised amount) or drastic (e.g. as in a carpal tunnel release (CTR) procedure). Pressure on the median nerve is relieved after cutting of the transverse carpal ligament. The incised skin is then sutured. The transverse carpal ligament remains open and the gap is slowly filled by scar tissue.
The mini-open technique utilizes a 1 to 1½ cm incision proximate the transverse carpal ligament. Various types of instruments can be placed through the incision. One or more of the instruments are used to cut or incise the transverse carpal ligament from underneath as appropriate.
In the endoscopic carpal tunnel release technique, a small horizontal incision is made at the wrist and an arthroscope is introduced underneath the transverse carpal ligament. A small knife or blade, attached to the end of the arthroscope, is utilized to incise or cut the transverse carpal ligament. Again, cutting through the transverse carpal ligament alleviates the compression on the median nerve. While the endoscopic carpal tunnel release technique is less invasive than the traditional, and is typically accomplished on an outpatient basis, it is nonetheless an invasive procedure that requires time to heal.
Moreover, with current invasive techniques, the surgeon must rely on his/her own expertise for visualization, not only for the initial incision on the palm of the hand, but also in locating where dissection of the transverse carpel ligament takes place. The place of dissection is critical because while it is desired to split the transverse carpal ligament, the surgeon must not lacerate any major branch of the median or ulnar nerves.
Furthermore, although current complication rates are low (approximately 3-4%), inadvertent laceration of a nerve (either fully or partially) can have catastrophic effects on the functionality of the patient's hand, as well as impact the surgeon's practice. Because of the risks, may patients suffering from carpal tunnel syndrome forego the surgical procedure because of the involved risks. Because of the above, various instruments and/or techniques have been developed.
In U.S. Pat. No. 6,494,882 issued to Lebouitz et al. on Dec. 17, 2002, there is disclosed a cutting instrument having integrated sensors on a metal blade thereof. The blade has a recess formed therein in which is disposed a sensor element. The sensor element includes a semiconductor substrate on which is formed a sensor, sensor array and/or one or more electrodes. The sensor, sensor array and/or one or more electrodes provide a signal to circuitry on the substrate for receiving and/or conditioning the received signals. The circuitry is connected to contacts to provide a means to output signals therefrom. The Lebouitz cutting instrument, however, is only able to receive signals with respect to locating a nerve. The nerve locating signals must therefore be generated external to the cutting instrument.
In U.S. Pat. No. 5,928,158 issued to Aristides on Jul. 27, 1999, there is disclosed a medical instrument having a nerve sensor. The nerve sensor is proximate a cutting blade of the medical instrument. Electronics to generate a nerve locator signal is disposed in the medical instrument. The nerve locator signal is provided to a patient by a remote patch that is connected to the electronics via an electrical lead. The patch is applied to a strategic location on the patient.
In U.S. Pat. No. 4,962,766 issued to Herzon on Oct. 16, 1990, there is disclosed a nerve locator and evaluator. The nerve locator and evaluator is mono-polar and is thus equipped with a single electrode at the evaluation tip. The Herzon nerve locator and evaluator therefore requires a secondary wire that is attachable to a patient's body via a conductive path such as via a needle or patch.
In U.S. Pat. No. 6,312,392 issued to Herzon on Nov. 6, 2001, there is disclosed a hand-held disposable surgical nerve evaluator and locator (i.e. device). The nerve evaluator and locator includes a housing that serves as a handpiece and that accommodates a printed circuit board, a DC voltage source, and a compressed gas source. The nerve evaluator and locator device includes switches for a nerve evaluation mode and a nerve locator mode. The nerve evaluator and locator device includes first and second electrical leads that serve as a nerve locator signal source and a nerve locator signal receiver. It is unclear, however, how the two electrical leads, being so close together, can locate a nerve.
It is therefore evident from the above that the previous instruments and/or techniques are not adequate. This is especially true with respect to techniques on the transverse carpal ligament.
It should thus be appreciated in view of the above, that it is desired to have a scalpel and/or scalpel system that provides for incision path evaluation, particularly with respect to nerve location.
It should thus be further appreciated in view of the above, that it is desired to have a scalpel and/or scalpel system that provides for evaluation of the appropriateness of the tissue targeted for incision.
It should thus be yet further appreciated in view of the above that it is desired to have a scalpel and/or scalpel system that performs various forms of evaluation.
It should thus be still further appreciated in view of the above that it is desired to have a scalpel and/or scalpel system that, in addition to the performance of various evaluations of the target tissue, is operative to perform incising of the target tissue.